Polglase Graeme R, Moss Timothy J M, Nitsos Ilias, Allison Beth J, Pillow J Jane, Hooper Stuart B
School of Women's and Infants Health, M094 The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia.
J Appl Physiol (1985). 2008 Aug;105(2):603-10. doi: 10.1152/japplphysiol.00041.2008. Epub 2008 Jun 5.
The effects of lung volume recruitment manouvres on pulmonary blood flow (PBF) during high-frequency oscillatory ventilation (HFOV) in preterm neonates are unknown. Since increased airway pressure adversely affects PBF, we compared the effects of two HFOV recruitment strategies on PBF and oxygenation index (OI). Preterm lambs (128+/-1 day gestation; term approximately 150 days) were anesthetized and ventilated using HFOV (10 Hz, 33% tI) with a mean airway pressure (Pao) of 15 cmH2O. Lung volume was recruited by either increasing Pao to 25 cmH2O for 1 min, repeated five times at 5-min intervals (Sigh group; n=5) or stepwise (5 cmH2O) changes in Pao at 5-min intervals incrementing up to 30 cmH2O then decrementing back to 15 cmH2O (Ramp group; n=6). Controls (n=5) received constant HFOV at 15 cmH2O. PBF progressively decreased (by 45+/-4%) and OI increased (by 15+/-6%, indicating reduced oxygenation) in controls during HFOV, which was similar to the changes observed in the Sigh group of lambs. In the Ramp group, PBF fell (by 54+/-10%) as airway pressure increased (r2=0.99), although the PBF did not increase again as the Pao was subsequently reduced. The OI decreased (by 47+/-9%), reflecting improved oxygenation at high Pao levels during HFOV in the Ramp group. However, high Pao restored retrograde PBF during diastole in four of six lambs, indicating the restoration of right-to-left shunting through the ductus arteriosus. Thus the choice of volume recruitment maneuvre influences the magnitude of change in OI and PBF that occurs during HFOV. Despite significantly improving OI, the ramp recruitment approach causes sustained changes in PBF.
肺容量复张手法对早产儿高频振荡通气（HFOV）期间肺血流量（PBF）的影响尚不清楚。由于气道压力升高会对PBF产生不利影响，我们比较了两种HFOV复张策略对PBF和氧合指数（OI）的影响。对早产羔羊（妊娠128±1天；足月约150天）进行麻醉，并使用HFOV（10Hz，吸气时间33%）进行通气，平均气道压（Pao）为15cmH₂O。通过将Pao增加到25cmH₂O持续1分钟，以5分钟的间隔重复5次来复张肺容量（叹息组；n = 5），或以5分钟的间隔逐步（每次5cmH₂O）改变Pao，增加到30cmH₂O然后再降至15cmH₂O（斜坡组；n = 6）。对照组（n = 5）在15cmH₂O下接受持续的HFOV。在HFOV期间，对照组的PBF逐渐降低（降低45±4%），OI升高（升高15±6%，表明氧合降低），这与在叹息组羔羊中观察到的变化相似。在斜坡组中，随着气道压力升高，PBF下降（下降54±10%）（r² = 0.99），尽管随后Pao降低时PBF没有再次升高。OI降低（降低47±9%），反映了斜坡组在HFOV期间高Pao水平时氧合改善。然而，高Pao恢复了6只羔羊中4只在舒张期的逆向PBF，表明通过动脉导管的右向左分流恢复。因此，肺容量复张手法的选择会影响HFOV期间OI和PBF变化的幅度。尽管显著改善了OI，但斜坡复张方法会导致PBF持续变化。
